Large scale structure in the Durham/UKST galaxy Redshift survey

Abstract

The initial results from the Durham/UKST Galaxy Redshift Survey are presented here. Using this redshift survey the luminosity, clustering and dynamical properties of galaxies in the Universe are investigated. The 3-D distribution of galaxies in the Durham/UKST survey appears "cellular” on 50-100h(^-1) Mpc scales (where h is Hubble's constant in units of 100 kms(^-1) Mpc(^-1)) and is clearly more complex than a simple 1-D periodic pattern. The optical galaxy luminosity function of the Durham/UKST survey is estimated and can be fit by a Schechter function. Comparison with other determinations of the luminosity function shows good agreement, favouring a flat faint end slope to M(_b J) ~ -14.The redshift space 2-point correlation function clustering statistic is estimated from the Durham/UKST survey. Comparison with previous estimates from other redshift surveys again shows good agreement and the Durham/UKST survey gives a detection of large scale power above and beyond that of the standard cold dark matter cosmological model on 10-40h(^-1)Mpc scales. The projected correlation function is also estimated from the Durham/UKST survey and is compared with models for the real space 2-point correlation function. To estimate this real space correlation function directly, a new application of the Richardson-Lucy inversion technique is developed, tested and then applied to the Durham/UKST survey. The effects of redshift space distortions on the 2-point correlation function are investigated and modelled in the non-linear and linear regimes. The 1-D pairwise velocity dispersion of galaxies is measured to be 416 ± 36 kms(^-1) which, while being consistent with the canonical value of ~ 350 kms(^-1) is slightly smaller than recently measured values. However, this value is inconsistent with the ~ 1000 kms(^-1) value as measured in the standard cold dark matter cosmological model at a high level of significance. The ratio of the mean mass density of the Universe, Ω, and the linear bias factor, b (relating the galaxy and light distributions), is then calculated to be Ω(^0.6)/b = 0.45 ± 0.38. This favours either an open (Ω < 1) and unbiased (b = 1) Universe or a flat (Ω = 1) and biased (b ~ 2) Universe.